Sam Winchester and Gordon Walker have never been on friendly terms due to their differences in hunting. They were temporary allies when hunting vampires but then turned into bitter enemies. Gordon sees Sam as the "Antichrist" and Satan's ally and tries to kill Sam. In the end, it was Sam who ended Gordon by beheading him.
When Sam and Dean Winchester meet Gordon, he and Dean connect easily. Sam is reluctant to trust Gordon as he sees him as reckless and after a warning from Ellen Harvelle, attempts to make Dean see sense but the two argue over Gordon. Gordon later refuses to listen when Sam explains that the vampires aren't evil and that they don't feed on humans but on animals. Gordon captures and tortures Lenore, even cutting Sam in order to tempt Lenore with human blood. Dean overpowers him and after the vampires escape, Gordon is left bound to a chair in an old farmhouse. It is later discovered Dean left him there for three days before alerting anyone.
Gordon is on Sam's trail, trying to kill him. He has found out from someone at the Roadhouse that Sam has psychic abilities, and knows from a demon he tortured that people like Sam are going to be soldiers on the side of evil in a coming war. Gordon uses Dean as bait, but Sam foils him, calling the police who arrest Gordon.Kubrick. He explains that contrary to Gordon's beliefs, he has found out that Sam was trying to keep the Devil's Gate in Wyoming from opening. Gordon states that he doesn't believe Sam is even human, and must be killed. A series of coincidences help Kubrick and Creedy track Sam down and they capture him but are foiled by Dean. Returning to Gordon, Kubrick now believes that he is on a mission from God to kill Sam. While Gordon obviously disbelieves this, he enlists Kubrick's help in planning his escape.
Gordon has escaped from prison, and tracks down Bela after he finds out she had been working with the Winchesters, convinced Sam is the Antichrist. Although he threatens to shoot her, she only reveals their whereabouts when Gordon gives her a priceless Mojo Bag. Along with Kubrick, Gordon interviews one of the victims of a vampire Sam and Dean are hunting, and tracks them down. The boys escape, but Gordon is captured by Dixon, who turns Gordon into a vampire. Gordon is determined to kill Sam as his last good act, before killing himself. He returns to see Kubrick but when Kubrick attacks him, Gordon kills him. Using a girl as bait, Gordon lures the boys to a warehouse, where Sam eventually kills him by garroting him with razor wire until he is beheaded.